1. Field of the Invention
The present invention relates to manufacturing of hydrogenated bisphenol-A-based epoxy resin, and more particularly, to a hydrogenation process that is performed under low-temperature, low-pressure conditions and facilitates improvement of yield of hydrogenated bisphenol-A-based epoxy resin.
2. Description of Prior Art
Bisphenol-A-based epoxy resin is one of the mot extensively used epoxy resins. Especially, hydrogenated bisphenol-A-based epoxy resin processed by hydrogenation does not contain double bonds and is unlikely to yellow, while having low viscosity, excellent processability and outstanding weatherability.
As shown in FIG. 1, a traditional hydrogenation reactor 10 for hydrogenating BPA-based epoxy resin has a vane stirrer 20, whose shaft 21 drives blades 22 at its terminal to stir a solution of bisphenol-A-based epoxy resin (hereinafter referred to as the liquid reactant) 30. High-pressure hydrogen gas is introduced through a hydrogen gas duct leading to the liquid reactant 30. The high pressure is applied to force contact between the hydrogen gas and the liquid reactant 30, so that the liquid reactant 30 performs desired hydrogenation reaction with the hydrogen gas in the presence of catalysts and produces hydrogenated bisphenol-A-based epoxy resin.
The conventional hydrogenation reactor 10 is less effective to contact the hydrogen gas with the liquid reactant 30, and consequently results in lower yield of hydrogenated bisphenol-A-based epoxy resin as a product of the hydrogenation reaction. For better yield, one approach is to make the hydrogenation reactor 10 as one providing a high-pressure reaction environment, yet this approach is costly and unfavorable to industrial production.
Among known skills in the art, U.S. Pat. No. 6,130,344 has disclosed a process for producing compound having epoxy group, which involves subjecting a compound having at a carbon-carbon unsaturated bond and an epoxy group to selective hydrogenation in the presence of a catalyst comprising rhodium or ruthenium at a reaction temperature of 30-150° C. under a reaction pressure of 1-30 MPa. This known technology has the following shortcomings:    1. Resulting high consumption of hydrogen gas, up to 30 MPa or 4351 lb/in2;    2. For acceptable reaction rate, requiring high reaction temperature, up to 150° C., which can make epoxy group decomposed; and    3. Requiring special equipment for dealing with high-pressure, high-temperature operation.
On the other hand, U.S. Pat. No. 6,060,611 has disclosed an aromatic epoxy resin that is made through hydrogenation under the conditions similar to those adopted in 006130344A Patent, namely a reaction temperature of 30-150° C. and a reaction pressure of 1-30 MPa, thus having the same shortcomings as happening to the above-mentioned U.S. Pat. No. 6,130,344, while suffering from a relatively low yield.